Small Molecule Allosteric Modulators for PTHR Signaling
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Solution Overview
Problem
Current drug discovery methods for class B GPCRs, such as those targeting hyperparathyroidism and osteoporosis, face challenges due to the difficulty in designing small molecule drugs that can effectively modulate the highly extended endogenous ligand binding region, leading to limited orally available options with side effects and high costs.
Innovation Solution
Development of small molecule allosteric modulators, specifically compounds like Pitt8 and Pitt12, that bind to an allosteric site on the parathyroid hormone (PTH) type 1 receptor (PTHR), negatively modulating receptor signaling and reducing cAMP production, thereby offering a therapeutic approach for hyperparathyroidism and osteoporosis without the limitations of peptidic drugs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If small molecule drugs are designed to target the highly extended endogenous ligand binding region of class B GPCRs, then the ability to modulate receptor signaling is improved, but the difficulty in effectively binding and modulating the receptor increases due to the large protein-protein interface
Solution Approach 1:
The patent segments the large extended ligand binding region into distinct functional domains: the peptide hormone binding region spanning the ECD, and the transmembrane domain binding region. By identifying and targeting specific pockets within these segments (such as the pocket formed by transmembrane helices), small molecules can effectively modulate receptor signaling without needing to perturb the entire large protein-protein interface.
Solution Approach 2:
The patent applies local quality by identifying specific localized pockets within the extended binding region that are accessible to small molecules. Rather than attempting to interact with the entire extended interface, the invention focuses on creating small molecules with specific structural features that target particular local regions (such as hydrophobic pockets near transmembrane helices), allowing effective modulation through localized interactions.
2Reliability
If peptidic drugs are used to target class B GPCRs, then the ability to effectively bind the extended ligand region is improved, but the oral accessibility and patient adherence decrease due to frequent injections required
Solution Approach 1:
The patent substitutes the mechanical/structural approach of peptidic drugs (which physically mimic the extended hormone structure) with a chemically-based approach using small organic molecules. These small molecules achieve receptor modulation through chemical interactions with specific pockets in the binding region, eliminating the need for injection and enabling oral administration while maintaining binding effectiveness.
3Measurement precision
If the entire extended ligand binding region is targeted, then the specificity of receptor modulation is improved, but the cost and complexity of drug development increase
Solution Approach 1:
The patent extracts the essential functional elements needed for receptor modulation from the entire extended ligand binding region. By identifying and targeting only the critical pockets (such as those formed by transmembrane helices) that are necessary for signaling modulation, the invention reduces drug development complexity while maintaining specificity through focused molecular design rather than attempting to target the entire extended interface.
Data Source
AI summary
Disclosed herein are methods for treating hyperparathyroidism, osteoporosis, or cancer cachexia, or inhibiting abnormally increased white adipose tissue browning, or decreasing the risk of a kidney stone in a subject, comprising administering to a subject in need thereof a therapeutically effective amount of a negative allosteric modulator of parathyroid hormone (PTH) type 1 receptor (PTHR) signaling.